Recent years, vacuum ultra violet (VUV) light having a wavelength equal to or less than 200 nm has been widely used not only in a semiconductor exposure field but also in other various fields. For example, a certain technique has been developed that patterns a self-assembled monolayer (hereinafter referred to as “SAM” or “SAM film”) by directly triggering a chemical reaction on the SAM with the light by use of the VUV light and a mask, without performing a pattern forming process by use of the photoresist.
More particularly, for example, Non-Patent Literature 1, which will be listed below, discloses that the VUV light is capable of performing the light patterning process of the SAM (i.e., self-assembled monolayer) without depending on a particular functional group. In particular, in the technique of NPL 1, an excimer lamp having the wavelength of 172 nm, which is used for eliminating the contaminant consisting of an organic substance, is employed as a light source for the exposure. This technique of NPL 1 focuses attention on the oxidative decomposition removal reaction of the SAM with the VUV light, and thus has been expected to be evolved for various kinds of optical micro-processing (micro-fabricating) of the SAM.
Meanwhile, as the vacuum ultra violet light source (hereinafter also referred to as “VUV light source”), conventionally, a low pressure mercury lamp having a bright line (or emission line) at the wavelength of 185 nm. On the other hand, nevertheless, it has been known that the VUV light within the wavelength band, in particular, equal to or less than 180 nm is capable of achieving the surface modification (for example, the asking or the like) at high speed. For this reason, recent years, a xenon excimer lamp that emits light having a wavelength of 172 nm has been mostly used as the VUV light source.
However, the above mentioned lamps emitting the VUV light generally have the longer light emitting part, in other words, the longer light emitting length. For example, the low pressure mercury lamp (i.e., “UL0-6DQ”, manufactured by USHIO DENKI KABUSHIKI KAISHA (USHIO Inc.)) has the light emitting length of 10 cm. Likewise, for example, the excimer light unit incorporating the xenon excimer lamp (i.e., “SUS06”, manufactured by USHIO DENKI KABUSHIKI KAISHA (Inc.)) has the light emitting length of 10 cm as well.
The VUV light emitted from those kinds of VUV lamps is a divergent light as the light emitting portion thereof has a substantially circular cylindrical shape. In the case of the divergent light, as it is difficult to perform the projection exposure, instead the contact exposure or the proximity exposure is supposed to be performed. In this case, the exposure to the to-be-irradiated object is affected by the wraparound (or speaking) of the divergent light. As a result, the pattern size that is to be resolvable is utmost approximately 100 μm of the line pattern width.
In order to achieve the miniaturization of the pattern line width (i.e., the fine pattern line width), it is required to employ the lamp that has a sufficiently short light emitting length and a higher light intensity of the vacuum ultra violet light to the extent being practically sufficient so as to be assumed to be a point light source, and to perform the exposure with little wraparound (sneaking) of the light. For this reason, as the light source to be used for patterning the SAM, it is conceivable to employ a flash lamp that has the light emitting length equal to or less than 12.5 mm and emits the VUV light having a sufficiently higher light intensity for the practical use. By combining the above mentioned flash lamp with a paraboloid mirror to be used, it makes it possible to achieve a light source device that is capable of extracting light that is the VUV light and also parallel or substantially parallel light. As such, a light irradiation device incorporating the above mentioned light source device is capable of achieving the miniaturization of the pattern line width (i.e., the fine pattern line width) in the patterning of the SAM.
It should be noted that an excimer laser device, which is used for the semiconductor exposure, can be also employed as another VUV light source other than the above mentioned lamps. According to an excimer laser exposure apparatus that incorporates such excimer laser device, it makes it possible to achieve the miniaturization of the pattern line width in the patterning of the SAM. However, the excimer laser device and the excimer laser exposure apparatus are considerably costly, thus it is impractical to employ the excimer laser device or the excimer laser exposure apparatus for the use other than the semiconductor exposure which is in the stage of commercial mass production, from the viewpoint of cost of ownership (COO). In other words, the excimer laser device can be employed only for the use in the limited field of industry that is proportional to the COO.